The Collection class defines the basic Java object model
representation and XML parsing/generation support for an
APP collection.
The implementation is versioned to support the AtomPub draft version 9
introspection format (used for the GData v1 implementation) as well
as the final RFC5023 format (used for all other versions). The key
difference between the two is that draft used an attribute for the
collection title and a comma-delimited list for accepted MIME types,
where the final version uses atom:title and repeating app:accept
elements.